Discarding vertices in geometry shader

vvvv beta question
1

i want to discard vertices in the geometry shader.

found a little example:

maxvertexcount(3)
void GS(
triangle VS_OUT vertices3,
inout TriangleStream<GS_OUT> outStream,
)
{
if (someCondition) // someCondition is a boolean that represents your condition
{
outStream.Append(vertices0);
outStream.Append(vertices1);
outStream.Append(vertices2);
}
else
{
// do not append to outStream, effectively discarding the output
}
}

concerning the conditions:

i saw a pic in the forum some time ago. seemed like cutting out vertices by texture. is this possible?

2

Yes it is. You can use SampleLevel to sample texture in VS or GS.

3

u can pretty much do the same in PS discarding pixels instead, i think that looks better

4

thx for replies! will try in pixelshader first. checked my openGL book, then found this:https://www.opengl.org/sdk/docs/tutorials/ClockworkCoders/discard.php